1. Field of the invention
The invention is based on a regulation method for a DC arc furnace.
2. Discussion of Background
Control of a DC arc furnace is known from EP 0 068 180 B1. There, independent control loops are provided in order to eliminate flickering phenomena 2, to be precise a current control loop having a converter as the actuating element and a voltage control loop having an electrode adjusting device as the actuating element, the output signal from the current regulator being added to the actual value of the DC voltage as a servo value.
Since the reactive power consumption of a mains-commutated rectifier depends on the operating point, the correction for load changes still always results in undesirable fluctuations in the reactive power, and hence the voltage, in the mains power supply. These voltage fluctuations produce fluctuating light intensities (flicker) in lighting systems, which can have a disturbing effect.
U.S. Pat. No. A-5,155,740 specifies a flicker compensation device for DC arc furnaces, in the case of which compensation device the converter is regulated only as a function of the detected current intensity of the arc furnace.
It is disadvantageous in this case that a relatively expensive power factor correction device is required. Where the electrocurrents are small, the reactive power of the furnace can become too small. With permanently installed capacitor banks, this leads to overcompensation which is frequently not accepted by mains power supply operators.